Yesterday evening's investigation by Michael Crick into the Andrew Mitchell affair revealed that an e-mail apparently corroborating the police logbook account of what took place didn't come from an ordinary eyewitness – as David Cameron believed when he read it. It appears to have been sent from the home computer of a member of the Diplomatic Protection Group. That person told Mr Crick that he didn't witness the incident and didn't send the e-mail either. The Times (£) reported yesterday that "a member of the Diplomatic Protection Group, the unit which guards Downing Street, had been
arrested on suspicion of gross misconduct".

Mr Crick's report suggested that the fabricated account was crucial to the Prime Minister deciding that Mr Mitchell was indeed at fault. If so, the former Chief Whip lost his career over a fabrication, and Mr Cameron should make a point of giving it back. But whether this is so or not, there are questions to be answered. Whose idea was the e-mail? Why did the sender purport to be an ordinary member of the public – indeed, to have been outside Downing Street at all on that fateful evening, which was untrue? Who wrote it? Who sent it? Who was aware of it? What light does it cast, if any, on the logbook account?

Mr Mitchell has called for a full inquiry into the incident. There is already a Police Complaints Commission inquiry into it, since a referral has been received from the Met. But which bodies conduct investigations is perhaps less important than how swiftly they report. The former Chief Whip's Cabinet career was destroyed by the allegations against him within a few weeks. It is thus only fair that inquiries into the matter don't drag on for many months. So the PCC should get a move on. The affair became known as Plebgate. After Mr Crick's revelations yesterday, wouldn't Smeargate be no less fair a description?